Dosimetric outcomes in prostate brachytherapy: is downsizing the prostate with androgen deprivation necessary?

OBJECTIVES: A large prostate volume has historically been a relative contraindication to prostate brachytherapy (PB) because of concerns of toxicity and potential pubic arch interference. Common practice has been to downsize large prostates with androgen deprivation therapy (ADT) before proceeding with brachytherapy. The present study compares postimplant dosimetry in patients with prostate volumes >50 cc with those with prostate volumes 50 cc (mean 58.1 cc, range 50.2-86.0 cc); the mean D(90), V(100), V(150), and V(200) was 125.1%, 95.2%, 68.2%, and 41.7%, respectively. The rectal V(100) was 1.0 cc for both cohorts. There was no statistically significant difference between the cohorts with respect to postimplant dosimetry for D(90), V(100), and V(150). The V(200) for prostate volumes >50 cc was significantly lower (p<0.05). CONCLUSIONS: In the present study, patients with prostate volumes >50 cc have postimplant dosimetry parameters similar to patients with prostate volumes

Overcoming pubic arch interference with free-hand needle placement in men undergoing prostate brachytherapy.

PURPOSE: The present study evaluates the postimplant dosimetry when free-hand needles were placed to overcome interference from the pubic arch. METHODS AND MATERIALS: A review of all patients who underwent prostate brachytherapy at our institution from 2001 to 2006 was performed. Postimplant dosimetry in men requiring free-hand needle placement was compared with postimplant dosimetry in men not requiring free-hand needle placement. RESULTS: Of the 145 patients who underwent prostate brachytherapy, 8 patients required free-hand needle placement. The mean prostate volume in the free-hand needle cohort was 46.0cc with a mean of 3.4 free-hand needles placed. In the 137 patients not requiring free-hand needle placement, the mean volume was 39.7cc. The mean D(90), V(100), V(150), and rectal V(100) for the free-hand cohort was 129.5%, 96.3%, 81.6%, and 1.45cc, respectively. The mean D(90), V(100), V(150), and rectal V(100) in men not requiring free-hand needle placement was 126.8%, 97.1%, 78.7%, and 1.03cc, respectively. CONCLUSION: The present study finds that adequate postimplant dosimetry can be obtained if free-hand needles are required due to pubic arch interference.